The present invention relates to an apparatus for washing hydraulic circuits involved in the preparation of milk-based beverages in machines for automatically dispensing hot drinks and/or in machines for preparing and supplying espresso coffee, said circuits comprising at least one first hydraulic path which extends between the milk storage vessel and the delivery device, at least one second hydraulic path which extends between a steam source and the same delivery device, a motor-driven pump arranged along said first hydraulic path, valve means situated along said second hydraulic path, a washing liquid source and means for connecting and disconnecting said washing liquid source to/from a point along said first hydraulic path.
As is known, in machines for automatically dispensing hot beverages and in professional automatic machines designed for bars, circuits and specific devices are used for heating and frothing the milk, the latter being in particular intended to form the beverage which is known by the name of “cappuccino”.
Such circuits comprise a milk source which may be a refrigerated storage vessel containing fresh milk or an apparatus which produces liquid milk by mixing, inside a special device, cold water with condensed milk drawn from its container by means of a special pump.
The milk, however supplied, is then conveyed by means of a pump to a delivery device which usually also performs the function of heating and forming the froth.
Heating of the milk is usually performed using the heat from condensation of the steam supplied by a special generator via an intercept valve. From the delivery device, the heated and in some cases frothed milk to which, where necessary, coffee is added flows into a cup situated underneath the spouts of the delivery device.
All the paths of the hydraulic circuit affected by the flow of the liquid milk, whether it be fresh or formed by means of dilution of the condensed milk, must be cleaned frequently and regularly and it is advisable for cleaning to be often accompanied also by a disinfecting operation.
The term “cleaning” used below in the present description is understood as meaning therefore washing operations which may be also combined with disinfecting operations and subsequent rinsing operations.
In accordance with the prior art, the circuit sections which are inside the delivery unit are cleaned by separating the said delivery device from the machine and disassembling its component parts. The operation is made easier by the fact that the delivery device is normally connected to the machine by means of a fast-action coupling which also connects both the hydraulic circuit from the milk storage vessel and the circuit from the steam source.
Cleaning of the circuits inside the machine, since they cannot be removed by the operator, is performed by activating processes which cause cleaning liquid to flow inside them.
In accordance with a conventional known cleaning technique, washing of the paths of the circuits inside the machine along which the milk flows provides the connection, by means of a special intercept valve, of these paths to an external source of washing liquid which may be water, to which disinfectant is added if necessary and which may also be hot, being supplied, for example, from the machine boiler. During the washing operation, the liquid is made to flow inside the hydraulic circuits which communicate with the exterior via the spouts of the delivery device. The liquid used is therefore continuously discharged without recycling. Since the action of the cleaning liquid is not immediate, in accordance with the prior art specified above, it is necessary for the liquid to flow for a certain period of time, therefore resulting in a large amount of washing liquid being used.
Moreover, especially in the case where hot or boiling water is used, the flow of this liquid outside the machine may result in the risk of scalding of the operator, should he/she inadvertently place a hand underneath the delivery device.
Examples of such known cleaning technique are described in EP 1,656,863 A1 and in EP 1,797,801 A1.
The object of the present invention is to simplify and automate the cleaning operations in machines of the type mentioned above, reducing the amount of cleaning liquid used and optimising at the same time the flushing efficiency produced by the washing liquid inside the hydraulic circuits undergoing treatment.